Architecture for simultaneous spectrum usage by air-to-ground and terrestrial networks

ABSTRACT

A network for providing air-to-ground (ATG) wireless communication in various cells may include an in-flight aircraft including an antenna assembly, a plurality of ATG base stations, a plurality of terrestrial base stations. Each of the ATG base stations defines a corresponding radiation pattern, and the ATG base stations are spaced apart from each other to define at least partially overlapping coverage areas to communicate with the antenna assembly in an ATG communication layer defined between a first altitude and a second altitude. The terrestrial base stations are configured to communicate primarily in a ground communication layer below the first altitude. The terrestrial base stations and the ATG base stations are each configured to communicate using the same radio frequency (RF) spectrum in the ground communication layer and ATG communication layer, respectively.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.15/637,460 filed Jun. 29, 2017, which is a continuation of U.S.application Ser. No. 15/287,914 filed Oct. 7, 2016 (which issued on Aug.8, 2017 as U.S. Pat. No. 9,730,077), which is a continuation of U.S.application Ser. No. 14/595,512 filed Jan. 13, 2015 (which issued onNov. 8, 2016 as U.S. Pat. No. 9,491,635), the entire contents of whichare hereby incorporated herein by reference.

TECHNICAL FIELD

Example embodiments generally relate to wireless communications and,more particularly, relate to techniques for enabling dual usage ofspectrum by wireless air-to-ground (ATG) networks and terrestrialnetworks in the same geographic area.

BACKGROUND

High speed data communications and the devices that enable suchcommunications have become ubiquitous in modern society. These devicesmake many users capable of maintaining nearly continuous connectivity tothe Internet and other communication networks. Although these high speeddata connections are available through telephone lines, cable modems orother such devices that have a physical wired connection, wirelessconnections have revolutionized our ability to stay connected withoutsacrificing mobility.

However, in spite of the familiarity that people have with remainingcontinuously connected to networks while on the ground, people generallyunderstand that easy and/or cheap connectivity will tend to stop once anaircraft is boarded. Aviation platforms have still not become easily andcheaply connected to communication networks, at least for the passengersonboard. Attempts to stay connected in the air are typically costly andhave bandwidth limitations or high latency problems. Moreover,passengers willing to deal with the expense and issues presented byaircraft communication capabilities are often limited to very specificcommunication modes that are supported by the rigid communicationarchitecture provided on the aircraft.

As improvements are made to network infrastructures to enable bettercommunications with in-flight receiving devices of various kinds, oneprospect that may be considered is the dedication of some amount ofradio frequency (RF) spectrum to in-flight communication. However, RFspectrum is extremely expensive due to the massive demands on thisrelatively limited resource. Accordingly, alternatives to the exclusivedesignation of a portion of RF spectrum to in-flight communication maybe of interest.

BRIEF SUMMARY OF SOME EXAMPLES

The continuous advancement of wireless technologies offers newopportunities to provide wireless coverage for aircraft in-flightwithout dedicating RF spectrum to such coverage. In this regard, forexample, by employing various interference mitigation strategies,spectrum reuse may be employed. Some example embodiments may provideinterference mitigation techniques that may allow spectrum reuse withina given area so that both terrestrial networks and air-to-ground (ATG)networks can coexist in the same geographical area and employ the samespectrum.

In one example embodiment, a network for providing air-to-ground (ATG)wireless communication in various communication volumes or cells isprovided. The network may include an in-flight aircraft including anantenna assembly, a plurality of ATG base stations, and a plurality ofterrestrial base stations. Each of the ATG base stations defines acorresponding radiation pattern, and the ATG base stations are spacedapart from each other to define at least partially overlapping coverageareas to communicate with the antenna assembly in an ATG communicationlayer defined between a first altitude and a second altitude. Theterrestrial base stations are configured to communicate primarily in aground communication layer below the first altitude to provide servicesindependently of or in cooperation with the ATG base stations. Theterrestrial base stations and the ATG base stations are each configuredto communicate using the same radio frequency (RF) spectrum in theground communication layer and ATG communication layer, respectively.

In another example embodiment, a method of selecting antenna elements ofan antenna assembly for communicating in an ATG network and compensatingfor aircraft movement (e.g., pitch and roll) is provided. The method mayinclude determining an expected relative position of an ATG base stationrelative to an in-flight aircraft, selecting an antenna element toemploy for communication with the ATG base station based on the expectedrelative position, receiving an indication of a change to the dynamicposition information (e.g., where the change is indicative of at least achange in the pitch or roll of the aircraft), and adjusting the selectedantenna element to compensate for the change to the dynamic positioninformation.

In another example embodiment, an antenna assembly for an aircraft isprovided. The antenna assembly may be capable of communicating with ATGbase stations of an ATG wireless communication network. The antennaassembly may include a plurality of antenna elements, at least one ofwhich is tiltable to maintain the antenna assembly oriented toward afocus region responsive to in-flight maneuvering of the aircraft.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING(S)

Having thus described the invention in general terms, reference will nowbe made to the accompanying drawings, which are not necessarily drawn toscale, and wherein:

FIG. 1 illustrates a top view of an example network deployment providingair-to-ground (ATG) wireless communication coverage areas in accordancewith an example embodiment;

FIG. 2 illustrates an aspect of an example network deployment of basestations providing overlapping cell coverage areas to achieve coverageup to a predetermined altitude in accordance with an example embodiment;

FIG. 3 illustrates a side view of a layered approach to providingwireless communication to in-flight aircraft while minimizinginterference between the layers in accordance with an exampleembodiment;

FIG. 4 illustrates a side panel element disposed on an in-flightaircraft in accordance with an example embodiment;

FIG. 5 illustrates a functional block diagram of antenna elements of anexample embodiment;

FIG. 6 illustrates a panel antenna vertical pattern in accordance withan example embodiment;

FIG. 7 illustrates a functional block diagram of a controller forselecting antenna elements and compensating for aircraft movement tokeep antenna elements oriented toward a focus region in accordance withan example embodiment;

FIG. 8 illustrates a block diagram of a method of communicating in anATG network in accordance with an example embodiment;

FIG. 9 illustrates a side view of a layered approach to providingwireless communication to in-flight aircraft including a high altitudeservice layer in accordance with an example embodiment;

FIG. 10 illustrates a full duplex radio architecture in accordance witha first example; and

FIG. 11 illustrates a full duplex radio architecture in accordance witha second option.

DETAILED DESCRIPTION

Some example embodiments now will be described more fully hereinafterwith reference to the accompanying drawings, in which some, but not allexample embodiments are shown. Indeed, the examples described andpictured herein should not be construed as being limiting as to thescope, applicability or configuration of the present disclosure. Rather,these example embodiments are provided so that this disclosure willsatisfy applicable legal requirements. Like reference numerals may beused to refer to like elements throughout. Furthermore, as used herein,the term “or” is to be interpreted as a logical operator that results intrue whenever one or more of its operands are true.

Some example embodiments described herein provide architectures forimproved air-to-ground (ATG) wireless communication performance. In thisregard, some example embodiments may provide for the use of basestations on the ground having antenna structures configured to generatea wedge-shaped cell inside which directional beams may be focused. Thewedge shaped cells may be spaced apart from each other and arranged tooverlap each other in altitude bands to provide coverage over a widearea and up to the cruising altitudes of in-flight aircraft. The wedgeshaped cells may therefore form overlapping wedges that extend outtoward and just above the horizon. Thus, the size of the wedge shapedcells is characterized by increasing altitude band width (or increasingvertical span in altitude) as distance from the base station increases.Meanwhile, the in-flight aircraft may employ antennas that are capableof focusing toward the horizon and just below the horizon such that theaircraft generally communicate with distant base stations instead ofbase stations that may be immediately below or otherwise proximal (e.g.,nearest) the aircraft. In fact, for example, an aircraft directly abovea base station would instead be served by a more distant base station asthe aircraft antennas focus near the horizon, and the base stationantennas focus above the horizon. This leaves the aircraft essentiallyunaffected by the communication transmitters that may be immediatelybelow the aircraft. Thus, for example, the same RF spectrum, and eventhe same specific frequencies the aircraft is using to communicate witha distally located base station may be reused by terrestrial networksimmediately below the aircraft. As a result, spectrum reuse can bepracticed relative to terrestrial wireless communication networks andATG wireless communication networks in the same geographic area.

A plurality of base stations may be distributed to provide acorresponding plurality of adjacent wedge shaped cell coverage areas.Each wedge shaped cell may define a coverage area that extends betweenan upper and lower altitude limit and the upper and lower altitudelimits may increase (substantially linearly) as distance from thetransmitters forming the wedge shaped cell increases. Thus, the coverageareas may be defined between altitude bands that increase in size andaltitude as they proceed away from the transmission site. A plurality ofsectors within each wedge shaped cell may combine to form the wedgeshaped cell. In some cases, six sectors may be employed to cover about30 degrees each for a total of 180 degrees of azimuth coverage providedby each wedge shaped cell. The cell coverage area may therefore besubstantially semicircular in the horizontal plane, and can be providedby multiple antennas each providing a wedge shaped sector overcorresponding portions of the semicircular azimuth. The base stationscan be deployed as substantially aligned in a first direction whileoffset in a second direction. For example, the base stations can also bedeployed in the first direction at a first distance to provide coverageoverlapping in elevation to achieve coverage over the predeterminedaltitude, and within a second distance in the second direction based onan achievable coverage area distance of the sectors. In someembodiments, any number of sectors may be employed for as much as 360degrees of coverage.

FIG. 1 illustrates a top view of a network 100 of deployed base stationsfor providing ATG wireless communication coverage as described above.Network 100 includes various base stations providing substantiallysemicircular cell coverage areas. The cell coverage areas are eachdepicted in two portions. For example, the cell coverage area for afirst base station is shown as similarly patterned portions 102 and 104.The portions 102 and 104 represent a single continuous cell coveragearea over a horizontal plane; however, FIG. 1 depicts interveningportion 108 of another cell coverage area as providing overlappingcoverage to achieve continuous coverage up to a predetermined altitude,as described further herein. Portion 102 is shown to represent theinitial cell coverage area from the location of the corresponding basestation out to an arbitrary distance for illustrative purposes; it is tobe appreciated that this portion 102 also includes the overlappingcoverage of portion 108 of another cell coverage area to achievecoverage at the predetermined altitude. Moreover, the coverage arearepresented by portions 106 and 108 may extend beyond boundary 130 ofcoverage area portion 104; the coverage areas are limited in thedepiction to illustrate at least one point where the bordering coverageareas are able to provide ATG wireless communication coverage at thepredetermined altitude. Further, the base stations are not depicted forease of explanation, but it is to be appreciated that the base stationscan be located such to provide the cell coverage area indicated byportions 102 and 104, portions 106 and 108, portions 110 and 112, etc.

The cell coverage areas 102/104 and 106/108 can be provided byrespective base stations in a first base station array, where the basestations of one or more base station arrays are substantially aligned ina first direction 120 (as depicted by the representative cell coverageareas). As shown, cell coverage areas 102/104 and 106/108 project adirectional radiation pattern that is oriented in the first direction,and are aligned front to back along the first direction. Such alignmentcan be achieved by substantially aligning base stations in the basestation array to provide the substantially aligned cell coverage areas,antenna rotation to achieve alignment in the cell coverage areas in thefirst direction 120, and/or the like. As described, in this regard, afirst base station that provides cell coverage area 102/104 can beoverlapped by at least a cell coverage area 106/108 of a second basestation in front of the first base station in the first direction 120.For example, a base station, or antennas thereof, can provide wedgeshaped cell coverage areas defined by multiple elevation angles employedby antennas transmitting signals to achieve a predetermined altitude bya certain distance from the base station. Thus, overlapping the cellcoverage areas in the first direction 120 allows cell coverage area106/108 to achieve the predetermined altitude for at least the certaindistance between the base station providing cell coverage area 102/104and a point along line 130 where the cell coverage area 102/104 achievesthe predetermined altitude.

In addition, base stations in the first base station array providingcell coverage areas 102/104 and 106/108 can be spaced apart (i.e.,located at random, fixed or predetermined intervals) in a seconddirection 122 from base stations of a second base station array, whichcan provide additional cell coverage areas 110/112, 114/116, etc.,aligned in the first direction 120. The first and second base stationarrays can extend substantially parallel to each other in the firstdirection 120. In addition, base stations of the second base stationarray can be offset from base stations of the first base station arrayin the first direction 120 (as depicted by the representative cellcoverage areas). The second direction 122 can be substantiallyperpendicular to the first direction 120 in one example. In thisexample, the first and second base station arrays can be offset toprovide the offsetting of respective cell coverage areas (e.g., theoffset shown between cell coverage areas 102/104 and 110/112), and anyother coverage areas of the base station arrays aligned in the firstdirection 120.

The first and second base station arrays can be spaced apart at agreater distance in the second direction 122 than base stations withinthe respective arrays spaced apart in the first direction 120. Forexample, the base stations can be spaced in the second direction 122according to an achievable coverage distance of the base stationproviding the cell coverage areas. Because the base stations providingcell coverage areas 102/104 and 106/108 in the first base station arrayare aligned in the first direction 120 such that cell coverage area106/108 provides overlapping coverage to cell coverage area 102/104 toachieve the predetermined altitude, the base station arrays themselvescan be separated based on the achievable distance of the respective cellcoverage areas 102/104 and 110/112. In this regard, no substantialoverlapping is needed between the boundaries of cell coverage areas102/104 and 110/112 provided by base stations of adjacent base stationarrays to reach the predetermined altitude since the altitudedeficiencies near the respective base stations are covered by cellcoverage areas of base stations in the base station array aligned in thefirst direction 120.

Moreover, offsetting the base stations providing the various cellcoverage areas over the second direction 122 can allow for furtherspacing in the first direction 120 and/or second direction 122 as theend portions of one cell coverage area in the horizontal plane can abutto a middle portion of another cell coverage area from a base station inan adjacent base station array to maximize the distance allowed betweenthe cell coverage areas while maintaining continuous coverage, which canlower the number of base stations necessary to provide coverage over agiven area. In one example, the spacing in the second direction 122 canbe more than twice the spacing in the first direction 120, depending onthe coverage distance of the cell coverage areas and the distance overwhich it takes a cell coverage area to reach the predetermined altitude.

As depicted, the spacing of a first distance between base stations in agiven base station array can be indicated as distance 140 in the firstdirection 120. The spacing of a second distance between base stationarrays in the second direction 122 can be indicated as distance 142.Moreover, the offset between the base station arrays can be indicated asa third distance 144. In one specific example, the distance 140 can benear 100 kilometers (km), where distance 142 between the base stationsproviding cell coverage area 102/104 can be 300 km or more. In thisexample, the achievable cell coverage areas can be at least 200 km fromthe corresponding base station in the direction of the transmittedsignals that form the coverage areas or related sectors thereof, as aslant distance from a base station within one array to the intersectingcoverage from a base station in the second array. Moreover, in thisexample, the distance 144 can be around 75 km.

In an example, the base stations providing cell coverage areas 102/104,106/108, 110/112, etc. can each include respective antenna arraysdefining a directional radiation pattern oriented in the firstdirection. The respective antenna arrays can include multiple antennasproviding a sector portion of the radiation pattern resulting in acoverage area that is wedge shaped in the vertical plane. For example,the cell coverage area provided by each antenna can have first andsecond elevation angles that exhibit an increasing vertical beam width,or span, in the vertical plane, and fills a portion of an azimuth in thehorizontal plane. Using more concentrated signals that provide smallerportions of the azimuth can allow for achieving further distance and/orincreased elevation angles without increasing transmission power. In thedepicted example, the cell coverage areas defined by the antenna arraysinclude six substantially 30 degree azimuth sectors that aresubstantially adjacent to form a directional radiation pattern extendingsubstantially 180 degrees in azimuth centered on the first direction todefine the semicircular coverage area. Each sector can be provided by anantenna at the corresponding base station, for example. Moreover, in oneexample, the base station can have a radio per antenna, a less number ofradios with one or more switches to switch between the antennas toconserve radio resources, and/or the like, as described further herein.It is to be appreciated that additional or a less number of sectors canbe provided. In addition, the sectors can have an azimuth more or lessthan 30 degrees and/or can form a larger or smaller total cell coveragearea azimuth than the depicted semicircular cell coverage area.

In yet other examples, the network 100 can implement frequency reuse ofone, three, four, seven, or other suitable configurations (e.g., usingformula N=î2+ĵ2+ij where i=# cells over from the original cell and j=#cells down from the original cell) such that nearby base stations canuse the same channels in providing the cell coverage areas. For example,a base station providing cell coverage areas 102/104 can use a firstchannel, a base station providing cell coverage area 106/108 in the samebase station array can use a second channel, and a base stationproviding cell coverage area 114/116 can use a third channel. Similarly,an adjacent group of three base stations providing cell coverage areasin a different base station array can use the same channels, etc. It isto be appreciated that other frequency reuse patterns and/or number ofreuse factors can be utilized in this scheme to provide frequencydiversity between adjacent cell coverage areas.

In a further example, a non-traditional frequency reuse scheme of twomay be employed by the system. The wedge shape of the base stationcoverage areas in combination with the directional aircraft antennaseffectively achieve a reuse of four with only two channel sets. In thisexample, an array of base stations alternate channel assignment betweentwo channels in the array, with Channel A on a first base station,Channel B on a second base station, Channel A on a third, etc. Thesecond array similarly alternates between the two channels, with ChannelA offset from the similar Channel A base station in the first array. Theoverlap area between the two arrays will occasionally present the sameco-channel frequency within the overlap area, but the angular directionsof arrival from the two co-channel base stations are sufficientlydistinct such that the aircraft antenna will focus on the closer basestation, resulting in an aircraft antenna null in the direction of thesecond, weaker base station. Thus, a non-traditional frequency reuse isachieved through the design of the wedge-shaped base station coverageand the design of the directional aircraft antennas.

Furthermore, in an example deployment of network 100, the firstdirection 120 and/or second direction 122 can be, or be near, a cardinaldirection (e.g., north, south, east, or west), an intermediate direction(e.g., northeast, northwest, southeast, southwest, north-northeast,east-northeast, etc.), and/or the like on a horizontal plane. Inaddition, the network 100 can be deployed within boundaries of acountry, boundaries of an air corridor across one or more countries,and/or the like. In one example, cell coverage area 106/108 can beprovided by an initial base station at a border of a country or aircorridor. In this example, a base station providing cell coverage area106/108, 110/112, and/or additional cell coverage areas at the border,can include one or more patch antennas to provide coverage at thepredetermined altitude from the distance between the base station to thepoint where the respective cell coverage area 106/108, 110/112, etc.reaches the predetermined altitude. For example, the one or more patchantennas can be present behind the cell coverage areas 106/108, 110/112,etc., and/or on the base stations thereof (e.g., as one or more antennasangled at an uptilt and/or parallel to the horizon) to provide cellcoverage up to the predetermined altitude.

FIG. 2 illustrates an example network 200 for providing overlappingcells (e.g., in the vertical direction) to facilitate ATG wirelesscommunication coverage at least at a predetermined altitude. Network 200includes base stations 202, 204, and 206 that transmit signals forproviding the ATG wireless communications. Base stations 202, 204, and206 can each transmit signals that exhibit a radiation pattern definedby a first and second elevation angle such to achieve a predeterminedaltitude. In this example, base stations 202, 204, and 206 providerespective wedge shaped cell coverage areas 212, 214, and 216 that areoffset in origin and overlap in the vertical direction. The basestations 202, 204, and 206 can be deployed as substantially aligned in afirst direction 120 as part of the same base station array, as describedabove, or to otherwise allow for aligning the cell coverage areas 212,214, and 216 in the first direction, such that cell coverage area 212can overlap cell coverage area 214 (and/or 216 at a different altituderange in the vertical plane), cell coverage area 214 can overlap cellcoverage area 216, and so on. This can allow the cell coverage areas212, 214, and 216 to achieve at least a predetermined altitude (e.g.,45,000 feet (ft)) for a distance defined by the various aligned basestations 202, 204, 206, etc.

As depicted, base station 202 can provide cell coverage area 212 thatoverlaps cell coverage area 214 of base station 204 to facilitateproviding cell coverage up to 45,000 ft near base station 204 for adistance until signals transmitted by base station 204 reach thepredetermined altitude of 45,000 ft (e.g., near point 130), in thisexample. In this example, base station 204 can be deployed at a positioncorresponding to the distance between which it takes cell coverage area214 of base station 204 to reach the predetermined altitude subtractedfrom the achievable distance of cell coverage area 212 of base station202. In this regard, there can be substantially any number ofoverlapping cell coverage areas of different base stations to reach thepredetermined altitude based on the elevation angles, the distance ittakes to achieve a vertical beam width at the predetermined altitudebased on the elevation angles, the distance between the base stations,etc.

In one specific example, the base stations 202, 204, and 206 can bespaced apart by a first distance 140, as described. The first distance140 can be substantially 100 km along the first direction 120, such thatbase station 204 is around 100 km from base station 202, and basestation 206 is around 200 km from base station 202. Further, in anexample, an aircraft flying between base station 206 and 204 may becovered by base station 202 depending on its altitude, and in oneexample, altitude can be used in determining whether and/or when tohandover a device on the aircraft to another base station or cellprovided by the base station to provide for uninterrupted handover ofreceivers on an aircraft.

Moreover, as described in some examples, base stations 202, 204 and 206can include an antenna array providing a directional radiation patternoriented along the first direction 120, as shown in FIG. 1, where thedirectional radiation pattern extends over a predetermined range inazimuth centered on the first direction 120, and extends between thefirst elevation angle and the second elevation angle of the respectivecoverage areas 212, 214, and 216 over at least a predetermined distanceto define the substantially wedge shaped radiation pattern. In thisregard, FIG. 2 depicts a side view of a vertical plane of the basestations 202, 204, and 206, and associated coverage areas 212, 214, and216. Thus, in one example, base station 202 can provide a cell coveragearea 212 that is similar to cell coverage area 106/108 in FIG. 1 in ahorizontal plane, and base station 204 can provide a cell coverage area214 similar to cell coverage area 102/104 in FIG. 1. Moreover, asdescribed, direction 120 can correlate to a cardinal direction,intermediate direction, and/or the like. In addition, in a deployment ofnetwork 200, additional base stations can be provided in front of basestation 206 along direction 120 until a desired coverage area isprovided (e.g., until an edge of a border or air corridor is reached).

As mentioned above, the establishment of an ATG network with basestations deployed and configured in the manner described in FIGS. 1 and2 provides the ability to create a layered approach to covering a givenarea, in which the layers define altitude bands in which distallylocated base stations provide coverage for aircraft with fore/aft andside looking antenna arrays that are essentially shielded frompotentially interfering transmitters directly below them. Accordingly,for example, a bottom layer (i.e., closest to the ground) may reuseradio spectrum already employed in the altitude bands defined in thelayer or layers above. Frequency reuse can therefore be employed for agiven region in distinct altitude bands.

FIG. 3 illustrates an example network architecture for providingoverlapping cells with layered altitude bands to facilitate ATG wirelesscommunication coverage with RF spectrum that can be reused by aterrestrial network. FIG. 3 shows only two dimensions (e.g., an Xdirection in the horizontal plane and a Z direction in the verticalplane), however it should be appreciated that the wedge architecture ofthe ATG network may be structured to extend coverage also in directionsinto and out of the page (i.e., in the Y direction). Although FIG. 3 isnot drawn to scale, it should be appreciated that the wedge shaped cellsgenerated by the base stations for the ATG portion of the networkarchitecture are configured to have a much longer horizontal componentthan vertical component. In this regard, the wedge shaped cells may havea horizontal range on the order of dozens to nearly or more than 100miles. Meanwhile, the vertical component expands with distance from thebase stations, but is in any case typically less than about 8 miles(e.g., about 45,000 ft).

As shown in FIG. 3, a terrestrial network component of the architecturemay include one or more terrestrial base stations 300. The terrestrialbase stations 300 may generally transmit terrestrial network emissions310 to serve various fixed or mobile communication nodes (e.g., UEs) andother wireless communication devices dispersed on the ground. Theterrestrial base stations 300 may be operably coupled to terrestrialbackhaul and network control components 315, which may coordinate and/orcontrol operation of the terrestrial network. The terrestrial backhauland network control components 315 may generally control allocation ofRF spectrum and system resources, and provide routing and controlservices to enable the UEs and other wireless communication devices ofthe terrestrial network to communicate with each other and/or with awide area network (WAN) such as the Internet.

The UEs of the terrestrial network may also transmit their ownterrestrial network emissions, which may create the possibility forgeneration of a substantial amount of communication traffic in a groundcommunication layer 320 extending from the ground to a predeterminedminimum altitude 325 above which only receivers on in-flight aircraft330 are present. The in-flight aircraft 330 may operate in an ATGcommunication layer 335 that may extend from one or two miles inaltitude up (e.g., the predetermined minimum altitude 325) to as far asabout 8 miles in altitude (e.g., a predetermined maximum altitude 340).While, the predetermined minimum altitude 325 and predetermined maximumaltitude 340 may bound a single ATG communication layer or, in the casewhere multiple ATG wedge shaped cells overlap, multiple ATGcommunication layers.

The architecture may also employ a first ATG base station 350 and asecond ATG base station 355, which are examples of base stationsemployed as described in the examples of FIGS. 1 and 2. Thus, forexample, the first ATG base station 350 may be deployed substantiallyin-line with the second ATG base station 355 along the X axis and maygenerate a first wedge shaped cell 360 that may be layered on top of asecond wedge shaped cell 365 generated by the second ATG base station355. When the in-flight aircraft 330 is exclusively in the first wedgeshaped cell 360, the in-flight aircraft 330 may communicate with thefirst ATG base station 350 using assigned RF spectrum and when thein-flight aircraft 330 is exclusively in the second wedge shaped cell365, the in-flight aircraft 330 may communicate with the second ATG basestation 355 using assigned RF spectrum. An area of overlap between thefirst wedge shaped cell 360 and the second wedge shaped cell 365 mayprovide the opportunity for handover of the in-flight aircraft 330between the first ATG base station 350 and the second ATG base station355, respectively. Accordingly, uninterrupted handover of receivers onthe in-flight aircraft 330 may be provided while passing betweencoverage areas of base stations having overlapping coverage areas asdescribed herein.

In an example embodiment, ATG backhaul and network control components370 may be operably coupled to the first and second ATG base stations350 and 355. The ATG backhaul and network control components 370 maygenerally control allocation of RF spectrum and system resources, andprovide routing and control services to enable the in-flight aircraftand any UEs and other wireless communication devices thereon tocommunicate with each other and/or with a wide area network (WAN) suchas the Internet.

Given the curvature of the earth and the distances between base stationsof the ATG network, the layering of the wedge shaped cells can beenhanced. Additionally, the first ATG base station 350 and the secondATG base station 355 may be configured to communicate with the in-flightaircraft 330 using relatively small, directed beams that are generatedusing beamforming techniques. The beamforming techniques employed mayinclude the generation of relatively narrow and focused beams. Thus, thegeneration of side lobes (e.g., radiation emissions in directions otherthan in the direction of the main beam) that may cause interference withcommunications in the ground communication layer 320 may be reduced. Insome cases, the terrestrial base stations 300, which are generally onlyrequired to transmit in a relatively narrow layer close to the ground,may also be configured to employ antennas and/or arrays that employ sidelobe suppression techniques aimed at reducing the amount of potentialinterference transmitted out of the ground communication layer 320 andinto the ATG communication layer 335.

Accordingly, the network architecture itself may help to reduce theamount of cross-layer interference. In this regard, the wedge shapedcell structure focuses energy just above the horizon and leaves a layeron the ground that is usable for terrestrial network operations withoutsignificant interference from the ATG base stations, and create aseparate higher altitude layer for ATG network communications.Additionally, the use of directional antennas with beamsteering by theATG base stations, and antennas with side lobe suppression, reduces theamount of interference across these layers. However, as will bedescribed in greater detail below, since all of the equipment in the ATGcommunication layer 335 with which communication is desired will be onthe in-flight aircraft 330, some embodiments may employ furtherinterference mitigation techniques associated with the antenna assembly375 provided on the in-flight aircraft 330. Accordingly, for example,the UEs or other wireless communication devices on or associated withthe in-flight aircraft 330 may be communicatively coupled with the firstATG base station 350 or the second ATG base station 355 via the antennaassembly 375 of the in-flight aircraft 330. In this regard, for example,the antenna assembly 375 may be strategically mounted on the in-flightaircraft 330 and/or the antenna assembly 375 may be operated orcontrolled in a manner that facilitates interference mitigation asdescribed in greater detail below.

By generally minimizing cross-layer interference, the same RF spectrumcan be reused in both the ground communication layer 320 and the ATGcommunication layer 335. As such, the network architecture of an exampleembodiment may effectively act as a frequency spectrum doubler in thatspectrum that is used in the terrestrial network may be reused by theATG network with minimal interference therebetween. The base stationsserving each respective layer may be distally located relative to eachother such that, for example, a serving ATG base station incommunication with the in-flight aircraft 330 is geographically locatedoutside a coverage area of each of the terrestrial base stations in aportion of the ground communication layer 320 above which the in-flightaircraft 330 is located. The substantially horizontally focused natureof the ATG base stations (350 and 355) enables them to be positioned faroutside of the region below which the in-flight aircraft 330 is located.The antenna assembly 375 can therefore “look” or otherwise focus itscommunication efforts away from potentially interfering sources directlybelow the in-flight aircraft 330.

As mentioned above, cross-layer interference mitigation may beaccomplished on the in-flight aircraft 330 by strategic positioning ofthe antenna assembly 375. For example, when the antenna assembly 375 ispositioned on a vertical stabilizer of the in-flight aircraft 330, theantenna assembly 375 may generally have a narrow aspect relative to theground and any transmissions directed from the ground, while providingexcellent control of the vertical antenna pattern. Additionally, forcertain side mountings of the antenna assembly on the body of thein-flight aircraft 330, part of the airframe may shield the antennaassembly 375 from terrestrial network emissions 310 generated byterrestrial base stations 300 below the in-flight aircraft 330. Suchshielding may be even more pronounced if, for example, the antennaassembly 375 is positioned on the top or roof of the in-flight aircraft330. In these examples, the metal airframe of the in-flight aircraft 330may act as an extended groundplane. The antenna assembly 375 in either(or both) of these locations may therefore have limited ability toreceive transmissions that are not directed from locations with asubstantially greater vertical component of distance from the in-flightaircraft 330 than the horizontal component of such distance. In otherwords, the antenna assembly 375 is shielded from transmitters that arenot near the horizon. These locations (e.g., on sides or tops ofaircraft) are therefore advantageous for further mitigating cross-layerinterference. However, such locations may generally be better forcommunication with transmitters off to the side of the in-flightaircraft 330, rather than in front of or behind the in-flight aircraft330. For better coverage in front of and behind the in-flight aircraft330, positioning of the antenna assembly 375 (or portions or componentsof the antenna assembly 375) on the bottom of the in-flight aircraft 330may be employed. Thus, fewer antenna elements (e.g., only those on thebottom of the in-flight aircraft 330) may need to have sophisticatedside lobe suppression techniques employed thereon to facilitatereduction of cross-layer interference.

In accordance with the general strategic positioning of the antennaassembly 375 described above, the antenna assembly 375 can be shielded(at least partially) from cross-layer interference by avoiding exposureto transmitters below the in-flight aircraft 330. However, such strategyimplies that the antenna assembly 375 should instead look totransmitters closer to the horizon. This horizon-focused paradigmactually fits quite well with the corresponding layered networkarchitecture described above since the ATG base stations are generallyconfigured to form wedge shaped cells that are focused just above thehorizon. Thus, both the ground transmitters and the antenna assembly 375of an example embodiment are mutually optimized for focusingsubstantially more energy in the horizontal plane than in the verticalplane. This enhances the ability to maximize spacing between ATG basestations (thereby reducing ATG base station count and network buildcost), and simplifies the architecture of the antenna assembly 375(since natural shielding of the airframe can be employed in some cases).As a result, corresponding ATG base stations focusing energy above thehorizon and airborne antenna assemblies focusing energy just below thehorizon are mutually optimized to communicate with each other withsubstantially less interference to worry about from terrestrial networkbase stations directly (or nearly directly) below the in-flight aircraft330 even when the same spectrum used by the terrestrial network isreused by the ATG network.

In an example embodiment, the antenna assembly 375 may be configured tofocus energy in an area from the horizon to about 10 or 15 degrees belowthe horizon (from the perspective of the in-flight aircraft 330). FIG. 4illustrates an example of the in-flight aircraft 330 having a side panelelement 400 as a portion of the antenna assembly 375. The side panelelement 400 is positioned on the vertical stabilizer, but couldalternatively be positioned on a side, top, bottom or other portion ofthe aircraft. Of note, the side panel element 400 may, in some cases, beembodied in a form other than as a flat array (e.g., as a blade antennaelement, a conformal array and/or the like). As can be appreciated fromthe example of FIG. 4, by focusing mainly on areas between the horizonand 10 or 15 degrees below the horizon, the subset of ATG base stationswith which communication can be established is somewhat limited.Accordingly, the side panel element 400 may need to be stabilized forensuring that it remains oriented toward the horizon and just below thehorizon even when the aircraft pitches (i.e., moves its head up and downas shown by arrow 410) or rolls (i.e., turns side to side as shown byarrow 420).

In some cases, the amount of pitch and roll that the in-flight aircraft330 may encounter may be limited based on certain restrictions that aredependent upon altitude, speed and passenger comfort. For example, pitch(i.e., the angle of ascent or descent) may be limited to about 7 degreesabove 10,000 ft in altitude. Meanwhile, for example, roll (i.e., theangle of bank right or left during a turn) may be limited to less than20 degrees above 10,000 ft in altitude and to less than 15 degrees above20,000 ft in altitude. Accordingly, not only may it be desirable toprovide compensation and/or stabilization of the antenna assembly 375(e.g., the side panel element 400), but such compensation and/orstabilization may be dependent upon altitude or other environmentalfactors.

In embodiments in which the antenna assembly 375 is embodied as orincludes a panel antenna (e.g., side panel element 400), which mayinclude a plurality of sector antennas. In some cases, the panel antennamay be mechanically and/or electrically steered or tilted to provide thecompensation and/or stabilization described above. As such, the panelantenna may also be referred to as a steerable matrix antenna. FIG. 5shows a block diagram of system components that may be employed inconnection with controlling an antenna assembly of an exampleembodiment. As shown in FIG. 5, the antenna assembly 375 may include aleft side panel element 402 and a right side panel element 404. Theantenna assembly may also include one or more blade, monopole or otherantenna elements such as antenna elements 406 and 408. In an exampleembodiment, element 408 may be a blade antenna configured for fore/aftreception. Meanwhile, the right and left side panel elements 404 and 402may be receive elements for respective sides of the airplane. Antennaelement 406 may be a blade antenna with four or more transmissionelements, and may have selectable directivity. In some embodiments, suchas for large airframes, the receive elements may optionally each becoupled to a remote radio head 430 via one or multiple cables. However,if no remote radio head is employed, the radio itself could performfunctions described herein in association with the remote radio head. Insome cases, the remote radio head 430 may be distributed in more thanone physical location (as shown by distributed elements (DEs) 432 and434. The remote radio head 430 may then be coupled (e.g., via fiberoptic or other cables) to a base radio 440 at which typical modulation,demodulation and other radio functions are conducted. The transmitelement 406 may also be coupled to the base radio 440.

In an example embodiment, the remote radio head 430 may provide forswitching among the receive antennas. In examples in which vertical beamsteering of the array panels is conducted, four or more cables may beused to connect each of the left side panel element 402 and the rightside panel element 404 to the remote radio head 430. The remote radiohead 430 may include one or more cavity filters corresponding to thenumber of antenna outputs provided to the remote radio head 430. Incases in which vertical beam steering is conducted with a mechanicaldevice adjusting the electrical tilt of the arrays, only one cable andcavity filter, bulk acoustic wave (BAW) filter, surface acoustic wave(SAW) filter, circulator or any other suitable filter may be employedfor each array. In some cases, the remote radio head 430 could beeliminated and filters, low noise amplifier (LNA) and switchingcomponents may be integrated into antenna housings or in other housingsproximate to the antennas. Switching components (whether part of orexternal to the remote radio head 430) would be used to select the bestantenna for receipt or transmission of any given signal based onlocation of the target or source, the signal strength of the ATG basestations, and the level of interference from surrounding base stationsor terrestrial stations. The antenna selection, then, has multipletriggers designed to maximize the signal to interference plus noiseratio.

FIG. 6 illustrates a panel antenna vertical pattern. When mounted on anaircraft such that the panel is focused generally perpendicular to thedirection of travel, compensation for aircraft rolling maneuvers may beneeded. As can be appreciated from FIG. 6, when the in-flight aircraft330 (which is generally communicating with ATG base stations at andslightly below the horizon) is rolling toward a ground station, theupper portion of the antenna pattern rolls toward the ground station.Meanwhile, when rolling away from the ground station, the antennapattern provides less gain toward the ground station. Thus, beamsteering may be needed (or at least helpful) to focus the antenna gainon the ground station by tilting the antenna assembly to compensate forthe aircraft roll. For the panel elements, mechanical or electricalsteering may be employed.

Accordingly, in some embodiments, the antenna assembly 375 may furtherbe in communication with a control element that may be configured tointerface with various aircraft sensors to determine the amount ofcompensation to apply to compensate for aircraft maneuvering. FIG. 7illustrates a block diagram of components that may be employed forcontrol of antenna assembly components (e.g., the side panels). As shownin FIG. 7, side panel element 400 may be operably coupled to a steeringassembly 500. The steering assembly 500 may be configured tomechanically or electrically tilt at least a portion of the antennaassembly 375 (e.g., the side panels (individually or collectively) ofthe side panel element 400) to maintain the side panels oriented tocommunicate with ATG base stations proximate to the horizon (e.g.,within about 15 degrees below the horizon). A controller 505 may beprovided in communication with the steering assembly 500 to providecontrol over the steering assembly 500. The controller 505 may includeprocessing circuitry 510 configured to provide control outputs forsteering of the side panel element 400 based on, for example, knowledgeof base station location and the relative position and orientation ofthe in-flight aircraft 330. The processing circuitry 510 may beconfigured to perform data processing, control function execution and/orother processing and management services according to an exampleembodiment of the present invention. In some embodiments, the processingcircuitry 510 may be embodied as a chip or chip set. In other words, theprocessing circuitry 510 may comprise one or more physical packages(e.g., chips) including materials, components and/or wires on astructural assembly (e.g., a baseboard). The structural assembly mayprovide physical strength, conservation of size, and/or limitation ofelectrical interaction for component circuitry included thereon. Theprocessing circuitry 510 may therefore, in some cases, be configured toimplement an embodiment of the present invention on a single chip or asa single “system on a chip.” As such, in some cases, a chip or chipsetmay constitute means for performing one or more operations for providingthe functionalities described herein.

In an example embodiment, the processing circuitry 510 may include oneor more instances of a processor 512 and memory 514 that may be incommunication with or otherwise control a device interface 520 and, insome cases, a user interface 530. As such, the processing circuitry 510may be embodied as a circuit chip (e.g., an integrated circuit chip)configured (e.g., with hardware, software or a combination of hardwareand software) to perform operations described herein. However, in someembodiments, the processing circuitry 510 may be embodied as a portionof an on-board computer. In some embodiments, the processing circuitry510 may communicate with various components, entities and/or sensors ofthe in-flight aircraft 330. Thus, for example, the processing circuitry510 may communicate with a sensor network 518 of the in-flight aircraft330 to receive altitude information, location information (e.g., GPScoordinates, latitude/longitude, etc.), pitch and roll information,and/or the like.

The device interface 520 may include one or more interface mechanismsfor enabling communication with other devices (e.g., modules, entities,sensors and/or other components of the in-flight aircraft 330). In somecases, the device interface 520 may be any means such as a device orcircuitry embodied in either hardware, or a combination of hardware andsoftware that is configured to receive and/or transmit data from/tomodules, entities, sensors and/or other components of the in-flightaircraft 330 that are in communication with the processing circuitry510.

The processor 512 may be embodied in a number of different ways. Forexample, the processor 512 may be embodied as various processing meanssuch as one or more of a microprocessor or other processing element, acoprocessor, a controller or various other computing or processingdevices including integrated circuits such as, for example, an ASIC(application specific integrated circuit), an FPGA (field programmablegate array), or the like. In an example embodiment, the processor 512may be configured to execute instructions stored in the memory 514 orotherwise accessible to the processor 512. As such, whether configuredby hardware or by a combination of hardware and software, the processor512 may represent an entity (e.g., physically embodied in circuitry—inthe form of processing circuitry 510) capable of performing operationsaccording to embodiments of the present invention while configuredaccordingly. Thus, for example, when the processor 512 is embodied as anASIC, FPGA or the like, the processor 512 may be specifically configuredhardware for conducting the operations described herein. Alternatively,as another example, when the processor 512 is embodied as an executor ofsoftware instructions, the instructions may specifically configure theprocessor 512 to perform the operations described herein.

In an example embodiment, the processor 512 (or the processing circuitry510) may be embodied as, include or otherwise control the operation ofthe steering assembly 500 based on inputs received by the processingcircuitry 510 indicative of ATG base station location and/or aircraftmaneuvering or position information. As such, in some embodiments, theprocessor 512 (or the processing circuitry 510) may be said to causeeach of the operations described in connection with the steeringassembly 500 in relation to adjustments to be made to antenna arrays toundertake the corresponding functionalities relating to arraycompensation/stabilization based on execution of instructions oralgorithms configuring the processor 512 (or processing circuitry 510)accordingly. In particular, the instructions may include instructionsfor processing 3D position information the in-flight aircraft 330(including orientation) along with position information of fixedtransmission sites in order to instruct an antenna array to tilt orotherwise orient in a direction that will facilitate establishing acommunication link between the antenna array and one of the fixedtransmission stations.

In an exemplary embodiment, the memory 514 may include one or morenon-transitory memory devices such as, for example, volatile and/ornon-volatile memory that may be either fixed or removable. The memory514 may be configured to store information, data, applications,instructions or the like for enabling the processing circuitry 510 tocarry out various functions in accordance with exemplary embodiments ofthe present invention. For example, the memory 514 could be configuredto buffer input data for processing by the processor 512. Additionallyor alternatively, the memory 514 could be configured to storeinstructions for execution by the processor 512. As yet anotheralternative, the memory 514 may include one or more databases that maystore a variety of data sets responsive to input sensors and components.Among the contents of the memory 514, applications and/or instructionsmay be stored for execution by the processor 512 in order to carry outthe functionality associated with each respectiveapplication/instruction. In some cases, the applications may includeinstructions for providing inputs to control operation of the steeringassembly 500 as described herein. In an example embodiment, the memory514 may store fixed position information indicative of a fixedgeographic location of ATG base stations.

The processing circuitry 510 may also be configured to receive dynamicposition information indicative of a three dimensional position andorientation of the in-flight aircraft 330 to compute an adjustment to beapplied (if needed) to the orientation of the side panel element 400based on in-flight aircraft 330 dynamic position. The antenna assembly375 may therefore be positioned optimally for engaging in continuedcommunication with the corresponding ATG base station currently beingused. The antenna assembly 375 can also be optimally positioned toanticipate handover to a next ATG base station based on a predictedfuture in-flight aircraft 330 location and the known locations of theATG base stations.

A further embodiment of the aircraft antenna may be as a long blademounted on the aircraft, with multiple antenna elements within theblade. The multiple elements are employed for beamforming that generallyprovides a horizon focused beam pattern. However, by using the longblade design, the horizon focused beam pattern can be achieved with amore narrow horizontal (azimuth) pattern (relative to that of the panelantenna) to focus gain toward the desired base station and reduce gainin other interfering directions. The blade results in a wider verticalantenna pattern (relative to the panel antenna), which obviates the needfor beam steering in the vertical direction to account for pitch orroll. The more narrow horizontal pattern in combination with the widervertical pattern delivers a smaller interference profile than the panelantenna, because less interference “surface area” is captured by theantenna pattern. However, the general horizon focus is maintained, andinterference from the ground communication layer 320 below the aircraftis substantially avoided.

The network 100 and its corresponding ATG base stations employing thewedge shaped cell architecture described above in reference to FIGS. 1and 2 may be employed to provide coverage for communication withreceivers on aircraft over a very large geographical area, or even anentire country. Moreover, using such architecture may substantiallyreduce or even minimize the number of ATG base stations that are neededto construct the network 100 since relatively large distances may beprovided between ATG base stations. Beamforming techniques (which mayalso be referred to as beam steering techniques) and frequency reuse maybe employed to further improve the ability of the network 100 to providequality service to multiple targets without interference. Moreover, byproviding a movable or steerable antenna array (e.g., antenna array 375)on the in-flight aircraft 330, particularly for an array that isshielded relative to transmissions directly (or nearly directly) belowthe in-flight aircraft 330 or is otherwise configurable to have lessgain anywhere other than near the horizon, both the ATG base stationsand the antenna array 375 may be configured to avoid interference belowthe in-flight aircraft 330. This may permit spectrum reuse of, forexample, ISM band frequencies (e.g., 2.4 GHz and/or 5.8 GHz) that may beunlicensed, or even licensed band frequencies at any desirable frequencyrange.

If airborne interference from ground transmitters such as, for example,ground based WiFi transmitters were relatively low over the entirety ofthe geographic area to be covered, it could be expected that the wedgearchitecture of the network 100 of FIGS. 1-2 could provide robust andcost effective coverage without any further modification even thoughground transmitters (e.g., terrestrial base stations 300) may useomni-directional antennas that are at least partially oriented totransmit upward using the same frequency.

As mentioned above, the ATG base stations (350 and 355) may employbeamforming (e.g., via a beamforming control module that may employ both2D knowledge of fixed base station location and 3D knowledge of positioninformation regarding the in-flight aircraft 330 to assist inapplication of beamforming techniques). Likewise, beamforming and/orbeamsteering may be employed on the antenna array 375 of the in-flightaircraft 330 to use knowledge of ATG base station location and aircraftmaneuvering (e.g., turns or pitch and roll) to maintain the antennaarray 375 in an advantageous orientation to communicate with the ATGbase stations when the in-flight aircraft 330 maneuvers. The antennaarray 375 may therefore be adjusted in a compensatory manner responsiveto maneuvering of the in-flight aircraft 330. The compensation employedmay involve switching between antenna elements that are best positionedfor the orientation of the aircraft relative to the location of aserving ATG base station and/or tilting of the antenna array 375 tomaintain the array in an advantageous position relative to the focusregion of the array.

Although not every element of every possible embodiment of the ATGnetwork 100 is shown and described herein, it should be appreciated thatthe communication equipment on the aircraft 330 may be coupled to one ormore of any of a number of different networks through the ATG network100. In this regard, the network(s) can be capable of supportingcommunication in accordance with any one or more of a number offirst-generation (1G), second-generation (2G), third-generation (3G),fourth-generation (4G) and/or future mobile communication protocols orthe like. In some cases, the communication supported may employcommunication links defined using unlicensed band frequencies such as2.4 GHz or 5.8 GHz. Example embodiments may employ time division duplex(TDD), frequency division duplex (FDD), or any other suitable mechanismsfor enabling two way communication within the system.

As indicated above, a beamforming control module may be employed onwireless communication equipment at either or both of the network sideor the aircraft side in example embodiments. Moreover, in someembodiments, the communications received at the aircraft side may bedistributed to equipment on the aircraft (e.g., such as telephonehandsets or UEs via a WiFi router or other wireless access point, oraircraft communication equipment). In some embodiments, informationdistributed from the wireless access point may be provided to passengerdevices or other aircraft communications equipment with or withoutintermediate storage.

In an example embodiment, the processing circuitry 510 may be configuredto conduct switching to select an antenna element among the antennaassembly for communication with an optimal or otherwise selected one ofthe ATG base stations. This switching may be performed to select aparticular antenna element (or sector) in a panel element or to selectbetween panel elements and/or other antenna elements (e.g., the bladeantenna) based on the location of the selected one of the ATG basestations relative to the in-flight aircraft 330. As mentioned above, theswitching may be performed using switch devices within the remote radiohead 430 or at another location. In some embodiments, the particularantenna element that is selected may additionally or alternatively betilted electrically or otherwise positionally adjusted to compensate orstabilize the particular antenna element responsive to maneuvering ofthe in-flight aircraft. Thus, for example, the processing circuitry 510may initially receive information indicative of dynamic positioninformation of the in-flight aircraft 330, which may include a 3Dposition and/or orientation information (e.g., pitch and roll) and/or anestimated future position. The processing circuitry 510 may determine anexpected relative position of a first network node (e.g., one of the ATGbase stations) relative to the aircraft (e.g., based on the fixedposition information indicating ATG base station location and thedynamic position information). Tracking algorithms may be employed totrack dynamic position changes and/or calculate future positions(relative or geographic) based on current location and rate anddirection of movement. After an expected relative position isdetermined, the processing circuitry 510 may be configured to provideinstructions to select an antenna element to communicate with the firstnetwork node in the focus region based on the expected relativeposition. Thereafter, any changes in dynamic position information,particularly related to pitch and roll, may be compensated for bysteering of the antenna element (e.g., mechanically or electrically).

FIG. 8 illustrates a block diagram of one method that may be associatedwith an example embodiment as described above. From a technicalperspective, the processing circuitry 510 described above may be used tosupport some or all of the operations described in FIG. 8. As such, theplatform described in FIG. 7 may be used to facilitate theimplementation of several computer program and/or network communicationbased interactions. As an example, FIG. 8 is a flowchart of a method andprogram product according to an example embodiment of the invention. Itwill be understood that each block of the flowchart, and combinations ofblocks in the flowchart, may be implemented by various means, such ashardware, firmware, processor, circuitry and/or other device associatedwith execution of software including one or more computer programinstructions. For example, one or more of the procedures described abovemay be embodied by computer program instructions. In this regard, thecomputer program instructions which embody the procedures describedabove may be stored by a memory device of a device (e.g., the controller505, and/or the like) and executed by a processor in the device. As willbe appreciated, any such computer program instructions may be loadedonto a computer or other programmable apparatus (e.g., hardware) toproduce a machine, such that the instructions which execute on thecomputer or other programmable apparatus create means for implementingthe functions specified in the flowchart block(s). These computerprogram instructions may also be stored in a computer-readable memorythat may direct a computer or other programmable apparatus to functionin a particular manner, such that the instructions stored in thecomputer-readable memory produce an article of manufacture whichimplements the functions specified in the flowchart block(s). Thecomputer program instructions may also be loaded onto a computer orother programmable apparatus to cause a series of operations to beperformed on the computer or other programmable apparatus to produce acomputer-implemented process such that the instructions which execute onthe computer or other programmable apparatus implement the functionsspecified in the flowchart block(s).

Accordingly, blocks of the flowchart support combinations of means forperforming the specified functions and combinations of operations forperforming the specified functions. It will also be understood that oneor more blocks of the flowchart, and combinations of blocks in theflowchart, can be implemented by special purpose hardware-based computersystems which perform the specified functions, or combinations ofspecial purpose hardware and computer instructions.

In this regard, a method according to one embodiment of the invention,as shown in FIG. 8, may include determining an expected relativeposition of an ATG base station relative to an in-flight aircraft atoperation 800. The expected relative position may be determined based oninformation indicative of aircraft location and information indicativeof the known fixed positions of ATG base stations. However, in somecases, the ATG base station location may be discovered based ondetection of a pilot signal or other transmissions from the ATG basestation. The method may further include selecting an antenna element toemploy for communication with the ATG base station based on the expectedrelative position at operation 810. The selected antenna element may bean element of an antenna assembly on the aircraft. The antenna assemblymay include transmission and receive components, and may include bladeantennas, panel antennas and/or the like. Thus, a selected antennaelement could be a particular panel antenna or blade antenna, or couldbe a particular sector of a panel antenna. The selected antenna elementcould be chosen based on signal strength measured or estimated, or otherfactors for base stations within a focus region (e.g., horizon to about15 degrees below the horizon) relative to the aircraft. At operation820, an indication of a change to the dynamic position information maybe received, and the change may be indicative of at least a change inthe pitch or roll of the aircraft. The selected antenna element may thenbe adjusted (e.g., by mechanical or electrical tilting) to compensatefor the change to the dynamic position information at operation 830(e.g., to keep the selected antenna element substantially orientedtoward the focus region based on the change to the dynamic positioninformation).

In an example embodiment, the layered approach described above could beaugmented to include an additional layer above the ATG communicationlayer. The layer above the ATG communication layer may be a highaltitude service layer. The high altitude service layer may be populatedwith high altitude service craft such as drones or other devices capableof flying (or orbiting) at high altitude. The high altitude servicecraft may be in communication with ground stations receivingcommunication signal from ATG base stations (or satellites) and relayingsuch communications on to the in-flight aircraft. However, the highaltitude service craft with which the in-flight aircraft communicate maybe located proximate to the horizon. The communication with highaltitude service craft proximate to the horizon allows the same verticalbeam steering antennas described above to be employed except thevertical beam steering antennas are steered to maintain the focus areajust above the horizon to locate distant high altitude service craftinstead of being steered to maintain the focus area just below thehorizon. The additional altitude may extend the spacing between servicestations (e.g., drones and/or ATG stations) that can be provided to givecontinuous coverage. Coverage can therefore be provided over sparselypopulated areas and/or oceans.

As shown in FIG. 9, the network of FIG. 3 may be provided with one ormore high altitude service craft 900 in a high altitude service layer910. The high altitude service layer 910 may extend above the ATGcommunication layer 335 (e.g., above the predetermined maximum altitude340) to high altitudes including low earth orbit and beyond. In someexamples, drones or balloons acting as high altitude service craft 900may loiter or otherwise operate as high as (or higher than) 50,000 ft to75,000 ft. However, it should be noted that the specific examplealtitudes described herein may change over time as aircraft capabilitieschange. The high altitude service craft 900 may communicate with the ATGbase stations (350 and 355) via an ATG link 920, with the in-flightaircraft 330 via an aircraft link 930 and/or with a satellite via asatellite link 940. Accordingly, the high altitude service craft 900 maybe enabled to service the in-flight aircraft 330 over vast distances andin different communication environments.

Accordingly, uninterrupted handover of receivers on the in-flightaircraft 330 may be provided while passing between coverage areas of ATGbase stations and high altitude service craft having overlappingcoverage areas as described herein. When employed in a network thatincludes a high altitude service layer 910, the antenna assembly 375 maybe configured to focus energy in an area from the horizon to about 10 or15 degrees above the horizon (from the perspective of the in-flightaircraft 330) to communicate with the high altitude service craft 900.Moreover, the antenna assembly 375 can be vertically steered to shiftbetween being serviced by ATG base stations or high altitude servicecraft based on signal strength or other such factors in association witha handover managed between the ATG base stations and high altitudeservice craft (or vice versa). The high altitude service craft 900 mayalso include antennas focused toward the horizon (e.g., focusing energyin an area from the horizon to about 10 or 15 degrees below the horizon(from the perspective of the high altitude service craft 900) and theservice craft antenna assembly may also be vertically steerable toaccount for turning or banking of the high altitude service craft 900 insimilar fashion to the way the antenna assembly 375 of the in-flightaircraft 330 is steerable (as described above). Thus, the high altitudeservice craft 900 may also use horizon-focused antenna assemblies forcommunication with aircraft, other drones and/or with the ground.Moreover, the same frequencies can be used for each of these links, andit may also be the same frequency used in the ground communication layer320 given that the beams for such communication are steerable (e.g.,employing spatial filtering and vertical beamsteering) to extendsubstantially parallel to the surface of the earth and avoidinterference with communications in the ground communication layer 320.In some cases, however, the high altitude service craft 900 may use afirst frequency to communicate to aircraft and ground stations, and theaircraft (where it does not use high altitude service craft 900 forconnectivity) may use a second frequency to communicate from theaircraft to ground and ground to ground.

The employment of the high altitude service layer 910 may effectivelycreate a sandwich mesh architecture. High altitude service craft 900 maylink to other high altitude service craft to provide a GB/s wirelessbackhaul network that may only selectively touch or access groundstations or satellites in a handful of places. The high altitude servicecraft 900 may therefore generally be above the weather and connectionsto the ground may be selectively made in areas that have good weather tominimize negative impacts of weather on communications at higherfrequencies, whether RF or optical. Furthermore, at high altitudes,physics may enable ready use of free space optics or high frequency RFto further enhance network performance. Meanwhile, the antenna assembly375 of the in-flight aircraft 330 is steerable +/−10 to 15 degrees fromthe horizon to selectively communicate with the ATG base stations (350and 355), with other in-flight aircraft 330 and/or with the highaltitude service craft 900.

As an alternative to the architecture of FIG. 5, in which separatereceive and transmit elements are provided, some embodiments may employa single steerable antenna element (or panel) that handles both transmitand receive functions by employing duplexing. By employing an antennaelement that can handle both transmit and receive functions, the size,weight, number and cost of antenna elements employed may be reduced.Maximal ratio combining may also be employed. With employment of fullduplexing, receiver filtering becomes important to allow signals to bedifferentiated. BAW filters, in-line cavity filters or a BAW duplexermay therefore be employed. A BAW duplexer may be a relativelystraightforward option for such a full duplex solution.

FIG. 10 illustrates a full duplex radio architecture in accordance witha first option. In this regard, FIG. 10 shows an architecture for arelatively long blade antenna 1000 that may be provided in someembodiments. The antenna 1000 may include one or more elements 1010(e.g., 10 in some cases) that may provide signals to a Butler combiner1020, which may be operably coupled to a multi-pole throw switch 1030(e.g., a ten pole switch). The switch 1030 may be operably coupled to acirculator 1040. The circulator 1040 may isolate signals among ports sothat signals on port 1 go to port 2, signals on port 2 go to port 3,etc. The circulator 1040 may provide as much as 18 dB of isolationport-to-port with a relatively low insertion loss of 0.6 dB. Thecirculator 1040 may be operably coupled to a receive filter 1050 andultimately to receiver circuitry 1060 via a low noise amplifier (LNA)1054 and a switch 1058. In this architecture, the receive filter 1050 isin front of the LNA 1054 for enhanced receiver overload protection(e.g., for a transmit signal level at the LNA input of −34 dBm, overallnoise figure may be 7.9 dB). The circulator 1040 is also operablycoupled to transmitter circuitry 1070 through a switch 1072, a cavityfilter 1080 and a power amplifier 1090.

FIG. 11 illustrates a full duplex radio architecture in accordance witha second option. In this regard, FIG. 11 shows an architecture for arelatively long blade antenna 1100 that may be provided in someembodiments. The antenna 1100 may include one or more elements 1110(e.g., 10 in some cases) that may provide signals to a Butler combiner1120, which may be operably coupled to a multi-pole throw switch 1130(e.g., a ten pole switch). The switch 1130 may be operably coupled to acirculator 1140. The circulator 1140 may isolate signals among ports sothat signals on port 1 go to port 2, signals on port 2 go to port 3,etc. The circulator 1140 may provide as much as 18 dB of isolationport-to-port with a relatively low insertion loss of 0.6 dB, asdescribed above. However, in this example, an LNA 1154 is provided priorto a receive filter 1150. The receive filter 1150 is then operablycoupled to the receiver circuitry 1160 via switch 1158. In thisarchitecture, the receive filter 1150 is behind the LNA 1154 for reducednoise figure, but higher transmit signal level at the LNA 1154 (e.g.,for a transmit signal level at the LNA input of +6 dBm, overall noisefigure may be 6.1 dB). The circulator 1140 is also operably coupled totransmitter circuitry 1170 through a switch 1172, a cavity filter 1180and a power amplifier 1190. In some alternative embodiments, either thearchitecture of FIG. 10 or the architecture of FIG. 11 could beduplicated with two duplexer elements replacing the circulators of eachrespective figure for an alternative approach.

Many modifications and other embodiments of the inventions set forthherein will come to mind to one skilled in the art to which theseinventions pertain having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Therefore, it is tobe understood that the inventions are not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of the appended claims.Moreover, although the foregoing descriptions and the associateddrawings describe exemplary embodiments in the context of certainexemplary combinations of elements and/or functions, it should beappreciated that different combinations of elements and/or functions maybe provided by alternative embodiments without departing from the scopeof the appended claims. In this regard, for example, differentcombinations of elements and/or functions than those explicitlydescribed above are also contemplated as may be set forth in some of theappended claims. In cases where advantages, benefits or solutions toproblems are described herein, it should be appreciated that suchadvantages, benefits and/or solutions may be applicable to some exampleembodiments, but not necessarily all example embodiments. Thus, anyadvantages, benefits or solutions described herein should not be thoughtof as being critical, required or essential to all embodiments or tothat which is claimed herein. Although specific terms are employedherein, they are used in a generic and descriptive sense only and notfor purposes of limitation.

What is claimed is:
 1. A wireless communication system comprising: anair-to-ground (ATG) communication layer defined by a plurality of ATGbase stations, the ATG base stations being configured to supportwireless communication in various cells defined by respective ones ofthe ATG base stations, the ATG base stations being configured to defineat least partially overlapping coverage areas to communicate with anantenna assembly of an in-flight aircraft in the ATG communicationlayer, the ATG communication layer being defined between a firstaltitude and a second altitude; a terrestrial communication layerdefined below the first altitude, the terrestrial communication layerbeing defined by terrestrial base stations and user equipment locatedbelow the first altitude; and a high altitude service layer disposedabove the second altitude, wherein the ATG base stations, theterrestrial base stations and devices in the high altitude service layerare each configured to communicate simultaneously using the same radiofrequency (RF) spectrum without inter-layer interference.
 2. The systemof claim 1, wherein the ATG base stations are each configured to definea corresponding radiation pattern focusing energy toward the horizon. 3.The system of claim 2, wherein a serving ATG base station from among theATG base stations is in communication with the in-flight aircraft whilebeing geographically located outside a coverage area of each of theterrestrial base stations in a portion of the ground communication layerabove which the in-flight aircraft is located.
 4. The system of claim 2,wherein a high altitude service craft in the high altitude service layeris configured to communicate with one or more other communication assetsabove the second altitude using the same RF spectrum.
 5. The system ofclaim 4, the high altitude service craft supports wireless communicationwith at least one asset outside the high altitude service layer.
 6. Thesystem of claim 4, wherein the high altitude service craft is disposedabove the second altitude to support wireless communication with asatellite.
 7. The system of claim 4, wherein the high altitude servicecraft is disposed above the second altitude to form an aircraft linkwith the in-flight aircraft in the ATG communication layer and asatellite link to a satellite.
 8. The system of claim 7, wherein thehigh altitude service craft forms an ATG link with a selected one of theplurality of ATG base stations.
 9. The system of claim 4, wherein thehigh altitude service craft is configured to communicate using verticalbeamsteering to focus energy proximate to the horizon.
 10. The system ofclaim 1, wherein the second altitude is greater than 50,000 feet. 11.The system of claim 1, wherein the in-flight aircraft comprises anantenna assembly that is steerable within a range of about 10 to 15degrees from the horizon.
 12. The system of claim 1, wherein the ATGcommunication layer is formed by both the ATG base stations and thein-flight aircraft using beamsteering to focus energy toward thehorizon.
 13. The system of claim 1, wherein responsive to the in-flightaircraft being located above a given geographic area, the in-flightaircraft communicates only with a distally located ATG base stationoriented within 10 to 15 degrees of the horizon relative to thein-flight aircraft, the distally located ATG base station being outsidethe given geographic area.
 14. An air-to-ground (ATG) network providingwireless communication to an in-flight aircraft capable of passingthrough various cells of the ATG network, the ATG network comprising: afirst ATG base station defining a first radiation pattern; a second ATGbase station defining a second radiation pattern; and a plurality ofadditional ATG base stations, each of which defines a correspondingradiation pattern, wherein the first, second and additional ATG basestations are spaced apart from each other to define at least partiallyoverlapping coverage areas to communicate with an antenna assembly on anin-flight aircraft in an ATG communication layer defined between aterrestrial communication layer and a high altitude service layer, andwherein the same radio frequency (RF) spectrum is employed in each ofthe ATG communication layer, the terrestrial communication layer and thehigh altitude service layer without inter-layer interference.
 15. TheATG network of claim 14, wherein the terrestrial layer extends from asurface of the earth to a first altitude, the ATG communication layerextends from the first altitude to a second altitude, and the highaltitude service layer extends above the second altitude.
 16. The ATGnetwork of claim 14, wherein the antenna assembly further includes oneor more antenna elements, and wherein a controller on the in-flightaircraft is configured to switch between the antenna elements of theantenna assembly based on a location of the in-flight aircraft.
 17. TheATG network of claim 16, wherein the antenna assembly is configured tocommunicate with a selected one of the first ATG base station, thesecond ATG base station or the additional ATG base stations based on theselected one of the first ATG base station, the second ATG base stationor the additional ATG base stations being in a focus region within thehorizon and about 15 degrees below the horizon relative to the in-flightaircraft.
 18. The ATG network of claim 17, wherein at least a portion ofthe antenna assembly is mechanically or electrically tiltable tomaintain the antenna assembly oriented toward the focus regionresponsive to maneuvering of the in-flight aircraft.
 19. The ATG networkof claim 18, wherein the controller is configured to receive sensor dataof the in-flight aircraft and, based on knowledge of ATG base stationlocation and orientation of the in-flight aircraft as indicated by thesensor data, provide a tilt instruction to compensate for themaneuvering of the in-flight aircraft.
 20. The ATG network of claim 18,wherein the controller is configured to receive sensor data of thein-flight aircraft and, based on knowledge of ATG base station locationand location or orientation of the in-flight aircraft as indicated bythe sensor data, provide a switch instruction to switch between antennaelements of the antenna assembly.